GRAVITATIONAL FIELDS

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• Created by: syaqub18
• Created on: 09-04-15 15:24
What is a Force Field?
A region in which a body experiences a force
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how is the gravitational field strength of a graviational field defined?
the strength, g, is the force per unit mass on a small test mass placed inside the field
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How is a radial gravitational field represented?
Field lines all around going towards the centre of the object
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How is a uniform gravitational field represented?
Field lines all parallel, the stronger the field the denser the field lines (more in an area)
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Is the gravitational field attractive, repulsive or both?
Always attractive
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Is gravity a scalar quantity or vector?
Vector because its direction is towards the centre of the object which has the gravitational field
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What quantity is g?
Vector
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What type of fields do point masses have?
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What is gravitational potential, V at a point?
The gravitational potential energy that a unit mass at that point would have (1 kg mass, has 10J of potential energy at point Z then gravitational potential is 10Jkg^-1
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What is the equation for gravitational potential?
V = - GM/r
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How does the graviational potential change from the surface?
Negative and increasing with distance from the mass
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What does the gradient of a curve of V (gravitational potential) against r (radius) show?
Gravitational field strength
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What is the gravitational potential at an infinite distance?
zero
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What is gravitational potential difference?
Energy needed to move a unit mass
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What happens when you move an object in a graviational field?
It does work against gravity
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What does the energy needed to do work against gravity depend on?
Mass of the object and the potential you move it through
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What is the relationship of an objects gravitational potential energy at a given gravitational potential?
dEp (gravitational potential energy) =mdV (d is for delta)
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What keeps planets and satellites in orbit?
Gravitational forces
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What is a satellite?
A smaller mass which orbits a larger mass
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What is the equation for orbital speed?
v = (Gm/r)^1/2
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Does the total energy of a satellite change or stay constant?
Remain constant
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Does the kinetic and potential energy change or stay constant?
The satellites speed and distance above the mass remains the same so constant
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In an elliptical orbit, when does the speed increase and what effect is there to the kinetic/potential energy?
When the height decreases (speed decreases when height increases) therefore kinetic energy increases as height decreases and potential increases and height increases.
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What are geosynchronous satellites?
Orbit directly over the equator and are always above the same point on the Earth.
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What is the angular speed of a geosynchronous satellite?
The same as the Earth
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What is the orbit of a geosynchronous satellite?
One day
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What are geosynchronous satellites used for and why?
For sending TV and telephone signals because satellite is stationary relative to the Earth to a certain point on the Earth so you don’t need to alter angle of the receiver.
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How are equipotential lines represented near the surface of the Earth?
as horizontal lines (parallel to the ground) as gravitational field over a small region is uniform
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Other cards in this set

Card 2

Front

how is the gravitational field strength of a graviational field defined?

Back

the strength, g, is the force per unit mass on a small test mass placed inside the field

Card 3

Front

How is a radial gravitational field represented?

Back Card 4

Front

How is a uniform gravitational field represented?

Back Card 5

Front

Is the gravitational field attractive, repulsive or both?

Back 